Geochemical prospecting



Patented Jan. 4, 1944 2.338.643 GEOCHEMICAL PBOSPECTING Leo Horvits, Houston, Tex.

No Drawing. Application July so, 1942,

SerialNo. 451,836

6 Claims. :(Cl. 23-232) The present invention is directed to geochemical' prospecting and especially to that type of collected which is prospecting in which soil samples are and treated for the liberation of a gas analyzed for its hydrocarbon content.

In my copending application Serial No. 305,896, I have described a process of the above identified type in which the soil samples are treated with a chemical suitable for disruption of waterinsoluble carbonates for the facilitation oi. the recovery therefrom 01' a gas. Among such chemicals are inorganic acids and salts which have an acid reaction in water solution.

In my Patentv No. I have described a method in which soil samples are treated withan acid capable of reacting with a metal to evolve iree hydrogen and the gas evolved is analyzed for its hydrogen content. In

this patent, I have described an embodiment in which, in order to ascertain that the hydrogen is not generated by the reaction between the acid and metal deposited by a-drill bit, the soil sample. in this case well cuttingais first treated witha solution of copper sulphate so as to remove any drill bit metal and is then treated with phosphoric acid to dissociate carbonates.

I have now found that a treatment of soil samples collected for the purpose of determining their hydrocarbon content with an aqueous solution 01' copper sulphate or a similar salt prior to the treatment 01' the sample with acid increases the amount of hydrocarbons recoverable from the sample. It is not clear why this should be so in view of the fact that aqueous solutions of salts, such as copper sulphate, are not as effective as acids for increasing the amount of hydrocarbons liberated from a soil sample. Salts which exhibit this property are in general these ttculariy bases the metal component of which is below iron in the electromotive series. b1'ii'he present invention is particularly applicae to inated with iron from the drill bit. In this embodiment the use of the acid salt increases the accuracy of the log. shown, as indicated abov that this is the case when the component or the liberated gas deter! mined is hyd'pgen. It has been found, however, that drill bit metal will react with strong mineral acids, such as phosphoric acid, to produce hydrocarbons by a mechanism that is not clearly understood. The acid salt, which in this case must be a salt or a metal below iron in the electromo- 2,278,929, issued April 7, 1942, i

It has previously been,

' either or both may be composed of strong acids and weak bases, parwell logging in which case there is a possibility that the cuttings collected may be contam- In a specific embodiment of the present invention, cuttings from a bore hole are, formed into a sample representative of a selected depth in the bore hole and this sample is treated with a saturated aqueous solution of copper sulphate for approximately 30 minutes. Then concentrated phosphoric acid is added and the entire mixture is heated in the usual manner. The gases are collected and analyzed for hydrocarbons by any one of several known microanalyti-- cal methods. The hydrocarbons determined can be concluded with certainty to have been present as such in the sample treated. Instead 01' using copper sulphate in this procedure, other copper salts such as copper chloride and copper acetate may be employed. Salts 01 silver and mercury may also be used with advantage.

It will be understood that the salt and the acid can be used conJointly or in sequence as described above. The latter is preferable in well logging. Usually a saturated aqueous solution of the salt and concentrated acid are employed, but used When used together they may be used in equal parts by volume.

The nature and objects 01' the present invention having been thus described, what is claimed as new and useful and is desired to be secured by Letters Patent is:

1. A method for geochemical prospecting in which sofl samples are collected and subjected individually to a treatment to liberate therefrom a gas sample which is analyzed for its hydrocarbon content, the step of treating each soil sample for the purpose of liberating a gas sample therefrom with an aqueous solution of an inorganic salt having an acid reaction and an inorganic acid.

2. A method according to claim 1 in which the inorganic salt has a base below iron in the elec tromotive series.

3. A method for log depicting the hydrocarbons with depth in a bore hole which comprises collecting samples of earth at spaced points along the bore hole, subjecting each sample successively to a treatment with an aqueous solution of a salt of a metal below iron in the electromotive series and a treatment with an inorganic acid, collecting the gas liberated by said treatments and analyzing said gas for its hydrotive series, particularly copper, removes the free carbon content.

4. A method according metal salt is a copper salt.

, 5. A method according to claim 3 in which the inorganic acid is phosphoric acid.

6. A method according to claim 3 in which the metal iscopper and the inorganic acid is phosphoric acid.

LEOHORVITZ.

to claim 3 in which the in a more dilute state.

producing a geochemical well variation in concentration of 

